Semi-final against Australia was watched as vividly in Buenos Aires as it was in Twickenham, In a country where football is the unofficial national religion, This weekend though, the spotlight was elsewhere.

In a country where football is the unofficial national religion, superstars such as Lionel Messi and Carlos Tevez are feted as working-class heroes: little geniuses whose talent took them from the poverty of the barrio to the heights of sporting glory. Then, of course, there is the man who still ranks close to God in the national psyche: Diego Armando Maradona.

This weekend though, the spotlight is elsewhere. Argentinian rugby was once associated here with the rich and prosperous, a game for those living in plush suburbs such as San Isidro, on the northern outskirts of the capital. Not any more. As Argentina’s Pumas prepare to take on Australia on Sunday at Twickenham in the semi-finals of the Rugby World Cup, the whole nation expects, including an emerging crop of young players from the impoverished slums where football once ruled supreme. Argentina’s World Cup triumphs have sealed rugby’s emergence as a truly mass sport in one of the world’s football heartlands.

The story of the progress of Argentinian rugby to the top table of the world game is also a tale of men like Mario Condorí. Last week Condorí greeted neighbours with a smile as he trundled through the waterlogged dirt streets of the giant, rambling slum “Villa 31” in downtown Buenos Aires. More than 40,000 of the city’s poorest people live here, piled together in two- and three-storey, mostly brick buildings that jut out in irregular shapes, teetering across 100 equally irregular-shaped blocks.

Promises by the city authorities to urbanise the area advance at a snail’s pace. The villeros, as they are called, sit on prime real estate, separated only by an elevated motorway from the city’s exclusive Recoleta neighbourhood, whose Parisian architecture, luxury shops and cosmopolitan and fashion-conscious inhabitants once earned Buenos Aires the nickname of “the Paris of South America”.

Condorí, 21, is on his way to the Bichito de Luz (Lightbug) children’s community centre, where his teammates are holding a garage sale of second-hand trainers to finance his beloved V31 rugby club. V31 are one of almost 100 rugby teams to have emerged in similar slums across Argentina in recent years, ever since a group of former players and coaches from the Pumas national team started giving their time and energy to training young players such as Condorí.

“Bringing rugby to the slum kids has been the greatest achievement in my life. It completely overshadows beating New Zealand or the Springboks, or England or France,” says Rodolfo O’Reilly, the 1980s Pumas coach who led the team to some of its best-remembered victories and who once sprinted naked across a pitch to celebrate a Pumas win.

From an Argentinian family of Irish descent, O’Reilly started playing rugby seven decades ago at the CASI (San Isidro Athletic Club), an upmarket rugby club set among the leafy and cobblestoned streets of San Isidro. It’s been a long road from that bastion of privilege to the muddy slums of San Fernando where he first started coaching underprivileged kids.

“Rugby is invisible to the eyes,” says O’Reilly, who was in Britain to witness Argentina’s famous quarter-final victory over Ireland last week.

O’Reilly laments the passing of the days when rugby was a purely amateur sport, scorning the high fees earned by some of today’s players. Today he devotes his energies to bringing rugby and the values it represents for him to Argentina’s populous slums. “It is a great tool for integrating, socialising and educating less-privileged kids,” he says.

Condorí couldn’t agree more. “What rugby teaches isn’t only physical. During the 80 minutes of the match there’s a lot of head-banging but in the third half after the game, you hug and share a meal with the other team. What happens on the pitch stays on the pitch, that’s one of the first things they taught us. In the third half you share only the good vibes.”

“There are now probably some 45,000 federated players between 15 and 23 years of age today in Argentina,” says Ignacio Silveyra, former coach of the team of the exclusive Champagnat school, also involved in taking rugby to the slums. “And we estimate there’s another 60,000 under-14s playing as well.”

Other former Puma stars have become involved. Condorí’s V31 team was born from Botines Solidarios (Solitary Rugby Boots), an association also taking rugby to the slums led by former star Ignacio Corleto, who played in France, winning three French championships for Narbonne between 2002 and 2007.

Corleto was also in Argentina’s squad when it reached third place in the 2007 Rugby World Cup, Argentina’s best result so far. Corleto calls what his association does “social rugby”, meaning that the sport helps integrate underprivileged kids into society. “You have to take rugby to the slums so it can become a vehicle for social and job inclusion for the kids,” Corleto maintains. “Rugby is a great equaliser.”

At the Virreyes club, O’Reilly has taken the inclusion motif a step further, setting up a scholarship programme that has financed university education for scores of the club’s players. “We have a strict policy regarding education,” says O’Reilly. “If a kid skips classes at school, we don’t let him play.” To encourage attendance, Virreyes provides meals for the kids after training sessions.

According to Coroní’s teammates, Daniel Lezcano and Darío Reyes, “rugby helps prevent kids from being out on the street with nothing to do”. With drugs, especially an Argentinian form of crack known as paco, a growing problem in the city’s slums, this is no mean feat. “We get lots of support from parents; rugby really helps keep kids sway from the temptation of drugs.”

Argentina’s improving performance in international matches, and the parallel lacklustre performance of its overpaid international soccer stars, has also attracted kids from the slums to the sport. “Rugby players play because they love the sport,” says Condorí. “It’s not a money sport, it’s a sport with moral values. The Pumas are not making dozens of millions like Messi or Tevez. Rugby is different – it’s not about individual stars. Neighbourhood clubs like ours, if we win, the whole team wins. Instead, in soccer, if a player scores, it’s all his own merit, and if he doesn’t, he gets all the blame.”

Taxi driver Diego Ferreira is another person disenchanted with Argentina’s football superstars. “Here in my cab, the conversation with passengers is more and more about rugby every day. People have grown tired of football players – they’re sissies, the slightest scrape and they’re squirming, crying on the ground. Instead rugby... well, you need to have guts to play rugby.”